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Active learning of deep surrogates for PDEs:application to metasurface design

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npj Computational Materials 2020年第1期6卷 312-318页

作者： Raphaël Pestourie Youssef Mroueh Thanh V.Nguyen Payel Das Steven g.johnson Department of Mathematics Massachusetts Institute of Technology77 Massachusetts AveCambridgeMA 02139USA IBM Research AI IBM Thomas J Watson Research CenterYorktown HeightsYorktownNY 10598USA MIT-IBM Watson AI Lab CambridgeMA 02139USA Iowa State University AmesIA 50011USA

Surrogate models for partial differential equations are widely used in the design of metamaterials to rapidly evaluate the behavior of composable ***,the training cost of accurate surrogates by machine learning can rapidly increase with the number of *** photonic-device models,we find that this training becomes especially challenging as design regions grow larger than the optical *** present an active-learning algorithm that reduces the number of simulations required by more than an order of magnitude for an NN surrogate model of optical-surface components compared to uniform random *** show that the surrogate evaluation is over two orders of magnitude faster than a direct solve,and we demonstrate how this can be exploited to accelerate large-scale engineering optimization.

关键词： optimization surrogate faster

Quantitative estimation of sediment erosion and accretion processes in a micro-tidal coast

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International Journal of Sediment Research 2014年第2期29卷 218-231页

作者： g.Udhaba DORA V.Sanil KUMAR P.VINAYARAJ C.S.PHILIP g.johnson CSIR-National Institute of Oceanography GoaIndia.Senior Research Fellow.Mr. CSIR-National Institute of Oceanography GoaIndia.Senior Principal Scientist.Dr. CSIR-National Institute of Oceanography GoaIndia.Project Assistant.Mr.

Spatio-temporal cross-shore profiles and textural characteristics are the key parameters for understanding dynamics of the inter-tidal sedimentary *** study describes short-term dynamics of the inter-tidal sedimentary environment at beaches along the micro-tidal *** a correlation is estimated in cross-shore morphodynamics and textural characteristics of surface *** sedimentary environment is examined for a complete annual cycle using monthly collected cross-shore profiles and sediment *** Devbag beach(northern side) and Ravindranath Tagore beach(southern side) at the Kali river mouth,Karwar,west coast of India are characterized from extremely gentle to average slope,and broadly composed of unimodal *** sedimentary environment is significantly composed of textures having fine to medium sand,well to moderately sorted,fine to coarse skewed,and platykurtic to leptokurtic in *** the annual cycle a reversal pattern is observed between the two adjacent beaches,where a slower rate of sediment accretion is observed at Devbag beach while Ravindranath Tagore beach exhibited *** beach dynamics along with the propagation of south-west(SW) and south-west-west(SWW) waves towards the coast significantly exhibit a dominance of northward sediment transport with the existence of a northerly alongshore *** addition,the study reveals that an eroded beach may not be significantly identified composed of coarse *** poor correlation in morpho-sedimentary characteristics reveals the prediction of grain characteristics based on beach profile and vice-versa is unrealistic.

关键词： Cross shore profile Beach volume grain size distribution Textural characteristics wave Kali estuary

Magnesium activation affects the properties and phosphate sorption capacity of poultry litter biochar

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Biochar 2023年第1期5卷 1117-1130页

作者： Joshua T.Padilla Donald W.Watts Jeffrey M.Novak Vasile Cerven James A.Ippolito Ariel A.Szogi Mark g.johnson United States Department of Agriculture Agricultural Research ServiceCoastal Plains SoilWater and Plant Research CenterFlorenceSC 29501USA School of Environment and Natural Resources The Ohio State UniversityColumbusOH 43210USA Center for Public Health and Environmental Assessment United States Environmental Protection AgencyCorvallisOR 97331USA

Biochars with a high affinity for phosphorus(P)are promising soil amendments for reducing P in agricultural *** litter(PL)is an abundant biochar ***,PL-derived biochars are typically high in soluble P and therefore require chemical modification to become effective P *** study investigated the effect of magnesium(Mg)activation on extractable P(EP)and P sorption capacities of PL-derived *** was produced at 500-900℃ from PL activated with 0-1 M *** differentially aged PL feedstocks were evaluated(1-,3-5-,and 7-9-year-old).Increased Mg activation level and pyrolysis temperature both resulted in EP reductions from the ***,biochars produced at temperatures≥700℃ from PL activated with≥0.25 M Mg had negligible EP.X-ray diffractograms indicated that increased Mg loading favored the formation of stable Mg_(3)(PO_(4))_(2) phases while increasing temperature favored the formation of both Mg_(3)(PO_(4))_(2) and Ca_(5)(PO_(4))_(3)*** P sorption capacities(Pmax)of the biochars were estimated by fitting Langmuir isotherms to batch sorption data and ranged from 0.66-10.35 mg g^(−1).Average Pmax values were not affected by PL age or pyrolysis temperature;however,biochars produced from 1 M Mg-activated PL did have significantly higher average Pmax values(pgreater abundance of ***,the results demonstrated that Mg activation is an effective strategy for producing PLderived biochars with the potential ability to reduce P loading into environmentally sensitive ecosystems.

关键词： sorption activation pyrolysis

Biochar compost blends facilitate switchgrass growth in mine soils by reducing Cd and Zn bioavailability

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Biochar 2019年第1期1卷 97-114页

作者： Jeffrey M.Novak James A.Ippolito Donald W.Watts gilbert C.Sigua Thomas F.Ducey Mark g.johnson Coastal Plains Soil Water and Plant Research CenterUnited States Department of AgricultureAgricultural Research ServiceFlorenceSC 29501USA Department of Soil and Crop Sciences Colorado State UniversityFort CollinsCO 80523USA National Health and Environmental Effects Research Laboratory United States Environmental Protection AgencyCorvallisOR 97331USA

Biochars have the potential to reclaim mine-impacted soils;however,their variable physico-chemical properties incite specu-lation about their successful remediation *** investigation examined the capability of biochars produced from three different feedstocks along with a compost blend to improve switchgrass growth conditions in a mine-impacted soil by examining influences on soil pH,grass metal contents,and soil-extractable metal ***(Cd)-and zinc(Zn)-contaminated mine soil was collected from a site near Webb City,Missouri,USA-a location within the Tri-State Min-ing *** a full factorial design,soil was treated with a 0%,2.5%,and 5%(w/w)compost mixture(wood chips+beef cattle manure),and 0%,2.5%and 5%of each biochar pyrolyzed from beef cattle manure,poultry litter,and lodgepole pine ***(Panicum virgatum,‘Cave-In-Rock’variety)was grown in a greenhouse for 50 days and the mass of shoots(above-ground biomass)and roots was assessed,while soil pH,deionized H_(2)O-and 0.01 M CaCl_(2)-extractable Cd and Zn concentrations were *** litter biochar and compost had the greatest ability to raise soil pH(from 4.40 to 6.61),beef cattle manure biochar and compost moderately raised pH(from 4.4 to 5.92),and lodgepole pine biochar and compost weakly raised pH(from 4.40 to 5.05).Soils treated with beef cattle manure biochar,poultry litter biochar signifi-cantly reduced deionized H_(2)O-and 0.01 M CaCl_(2)-extractable Cd and Zn concentrations,while lodgepole pine biochar-treated soils showed mixed *** shoot and root masses were greatest in soil treated with compost in combination with either beef cattle manure biochar or poultry litter *** treated with 5%beef cattle manure biochar+5%compost had greater reductions in total Cd and Zn concentrations measured in switchgrass shoots and roots compared to the other two *** three biochars and compost mixtures applied to heavy metal,mine-im

关键词： Biochar Heavy metals Metal sorption Tri-State Mine soil Remediation Switchgrass

Microbial response to designer biochar and compost treatments for mining impacted soils

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Biochar 2021年第3期3卷 299-314页

作者： Thomas F.Ducey Jeffrey M.Novak gilbert C.Sigua James A.Ippolito Hannah C.Rushmiller Donald W.Watts Kristin M.Trippe Kurt A.Spokas Kenneth C.Stone Mark g.johnson Coastal Plains Soil Waterand Plant Research CenterAgricultural Research Service-USDAFlorenceSCUSA Department of Soil and Crop Sciences Colorado State UniversityFort CollinsCOUSA National Forage Seed Production Research Center Agricultural Research Service-USDACorvallisORUSA Soil and Water Management Research Unit Agricultural Research Service-USDASt.PaulMNUSA National Health and Environmental Effects Research Laboratory US Environmental Protection AgencyCorvallisORUSA

The Oronogo-Duenweg mining belt is a designated United States Environmental Protection Agency Superfund site due to lead-contaminated soil and groundwater by former mining and smelting *** that have undergone remediation-in which the O,A,and B horizons have been removed alongside the lead contamination-have an exposed C horizon and are incalcitrant to revegetation *** also continue to contain quantifiable Cd and Zn *** improve soil conditions and encourage successful site revegetation,our study employed three biochars,sourced from different feedstocks(poultry litter,beef cattle manure,and lodgepole pine),at two rates of application(2.5%,and 5%),coupled with compost(0%,2.5%and 5%application rates).Two plant species-switchgrass(Panicum virgatum)and buffalograss(Bouteloua dactyloides)-were grown in the amended *** of soils with poultry litter biochar applied at 5%resulted in the greatest reduction of soil bioavailable Cd and ***-ground biomass yields were greatest with beef cattle manure biochar applied at 2.5%with 5%compost,or with 5%biochar at 2.5%and 5%compost *** microbial biomass was achieved with 5%poultry litter biochar and 5%compost,and microbial communities in soils amended with poultry litter biochar distinctly clustered away from all other soil ***,poultry litter biochar amended soils had the highest enzyme activity rates forβ-glucosidase,N-acetyl-β-D-glucosaminidase,and *** results suggest that soil reclamation using biochar and compost can improve mine-impacted soil biogeophysical characteristics,and potentially improve future remediation efforts.

关键词： Biochar Compost Microbial response Mine soil reclamation Plant growth